Silvery Lupine

Lupinus argenteus

by Kathy Lloyd, Montana Native Plant Society

Silvery lupine, or Lupinus argenteus, is one of seven plants that were collected on July 7, 1806 by
Meriwether Lewis, making this the most productive day for plant collecting in Montana. We know that
at least seven species were collected because the specimens still exist and are housed in the Lewis
& Clark Herbarium at the Academy of Natural Sciences in Philadelphia. On July 7th, Lewis and
his small band of men were traveling along the Cokahlaishkit River, today called the Blackfoot
River, in Lewis & Clark County. On that day Lewis and his party traveled from their camp on
Beaver Creek, along the Blackfoot River and over the Continental Divide at present-day Lewis &
Clark Pass to their camp for the night about three miles east of Table Mountain. Lewis and his men
traveled 32 miles that day. Despite the ascent of Lewis & Clark Pass and the long miles
traveled, Lewis still managed to collect plant specimens and write in his journal. What a hardy and
trail-toughened group of men they were!

Lewis and his group of men were traveling by horseback to their cache left at White Bear Island
the previous summer. Lewis and a few companions then planned to explore the Marias River drainage
while the remainder of Lewis's men would portage around the Great Falls with the baggage and canoes
and meet Lewis at the confluence of the Marias and Missouri Rivers. Lewis says in his journal on
July 1, 1806, " from this place [Traveler's Rest] I determined to go with a small party by the most
direct rout to the falls of the Missouri, there to leave Thompson McNeal and goodrich to prepare
carriages and geer for the purpose of transporting the canoes and baggage over the portage, and
myself and six volunteers to ascend Maria's river with a view to explore the country and ascertain
whether any branch of that river lies as far north as Latd. 50 "

The silvery lupine specimen in the Lewis & Clark Herbarium has a label written by Frederick
Pursh, the botanist who was retained to look at the expedition's plant collection, that reads, "On
the Cokahlaishkit. Jul. 7th 1806. Flowers yellowish white." This specimen is one that was found
tucked away at the American Philosophical Society and was believed lost. There is another specimen
of silvery lupine at the Herbarium, Royal Botanic Gardens in Kew, Surrey, England. Modern day Lewis
and Clark botanical scholars believe this specimen was probably collected in Idaho in June 1806,
even though the label says July 1806. Indeed, in his journal on June 5, 1806 Lewis mentions
observing "several of the pea blume flowering plants" and it is possible one may have been this
species, although other members of the bean (pea) family, or Fabaceae, were observed and collected
as well.

As do all lupines, silvery lupine has palmately compound leaves with six to nine leaflets that
join together at a common point. The silky-haired leaves are opposite on the stem and at times have
a silvery sheen that may explain the origin of the common name. In fact, argenteus is from a Greek word for silver. The plants are from six to 24 inches high with
one to several stems that are often branched. The flowers have the typical look of pea flowers,
with a banner, two wings and a keel. The banner petal usually has a white spot on it that serves as
a signal for pollinators, often bees. As the flower ages the spot turns a reddish color and bees
have learned to skip these flowers as the nectar reward will be limited. This helps the bees by
directing them to flowers with fresh and ample nectar, and helps the plant by keeping old pollen
out of circulation. The flower racemes are usually four to six inches high with numerous individual
flowers around the flowering stem. The flowers can be white or nearly white with a bluish tinge, to
light or dark blue. Lewis evidently collected a whitish colored individual. The pods that form
after flowering is complete hold two to five pinkish-gray to light brown seeds.

Silvery lupine is found in grasslands, ponderosa pine woodlands, on rocky prairie hillsides and
on subalpine ridges. The species is distributed from east-central Oregon to northern California and
east to South Dakota and the Rocky Mountain states to New Mexico. It is common in the Great Basin
and Great Plains but is rare in Saskatchewan and Kansas. It can be found today on Lewis & Clark
Pass where Lewis collected it in 1806.

Lupinus is derived from the Latin word lupus, meaning wolf. The connection is not clear but several theories have been advanced.
A she-wolf was regarded as the wetnurse of Rome, so it may be a term of fond affection. Or, more
commonly promoted is the theory of lupines as sheep-killers, as were wolves. Lupines, including
silvery lupine, are considered poisonous to livestock, especially sheep. The seeds contain the most
concentrated toxic principle, but the toxin is not cumulative. A great quantity has to be eaten at
one time for toxic effects to be exhibited. Poisoned sheep may froth at the mouth, have labored
breathing and convulsions. Lupines can be valuable forage if proper grazing techniques are employed
and plenty of other forage is available. They are considered to increase under grazing
pressure.

Silvery lupine, as are all members of the bean family, is an important nitrogen fixer and makes
that nutrient available for other plants. Since they often grow is areas with poor soil
development, their presence helps increase soil fertility to the benefit of plant diversity.

The native inhabitants that Lewis and Clark encountered on their journey had uses for numerous
native plants, and lupine was no exception. The Blackfoot used an infusion of lupine, which species
is not clear, to relieve indigestion and gas, and to quell hiccups. Sacagawea's people, the
Shoshone, used lupine as a diuretic. Various Indian tribes used lupine as animal fodder and some
used the roots, leaves or young plants as food for themselves. Lupine was used as incense in the
Ghost Dance and male Blackfoot warriors chewed the leaves ceremonially before beginning face
painting.

Today we enjoy silvery lupine as it dots the hillsides with blue, and as an easy-to-care-for
native plant in gardens and landscape plantings. Varieties of domesticated lupine have been
developed for garden use, but our native species is attractive and adapted to our environment.

When you see silvery lupine remember the role it played in Montana history and the importance of
preserving its prairie and ridgetop habitats, many of which may be threatened by weed invasions and
off-road vehicle travel.